Differential overmolded weldable ring

ABSTRACT

A differential assembly is disclosed herein. The differential assembly includes a case, a weld ring and a ring gear. The ring gear and case may comprise dissimilar materials. The case may be overmolded onto the weld ring. The weld ring may be welded to the ring gear such that the ring gear is attached to the case.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent ApplicationNo. 62/354,161 entitled “DIFFERENTIAL OVERMOLDED WELDABLE RING,” filedon Jun. 24, 2016, which is incorporated herein by reference in itsentirety.

FIELD OF INVENTION

The present disclosure relates to a differential assembly. Inparticular, the present disclosure relates to a differential case withan overmolded ring to which a ring gear may be welded to form adifferential assembly configuration suitable for a wide variety ofapplications including, but not limited to, a differential for anautomobile or a ring gear welded to a shaft.

BACKGROUND

A differential is part of a power train of a vehicle that allows anengine to transmit torque and rotation to wheels. The differentialallows an outer drive wheel to rotate at a different rate than an innerdrive wheel when the vehicle turns. It includes gears or a gear trainthat are driven by an input shaft to drive output shafts connected tothe gears.

A propeller shaft or drive shaft connects to a pinion, and the piniondrives a ring gear of the differential. The ring gear is attached to adifferential case or housing and may include teeth for driving othergears or pinions. Traditionally, bolts connect the ring gear with adifferential case to prevent movement of the ring gear with respect tothe differential case. In other examples, ring gears may be welded orbrazed to the differential case.

In some automobiles, a lay shaft transmits power or torque in adrivetrain. These shafts can include toothed gears bolted to or castwith the lay shaft. The input torque and the load on the shafts mayrestrict the types of materials suitable for the shaft.

Welding or brazing puts limitations on the number and type of materialsthat can be used. In some differentials, the differential case and thering gear comprise the same or similar materials, such as iron. Havingthe same material may allow the ring gear and case to be weldedtogether. If non-similar materials are welded together, the coefficientof thermal expansion mismatch or other differences between the materialsmay lead to cracks, or other undesired results. For example, welding ofiron may leave brittle microstructural constituents and residual stressthat may lead to cracking at a joint. In other instances, a ring gear isattached to a case via bolts and other fasteners that add weight andcomplexity to the assembly. Further, these methods require additionalparts, materials, steps, and the like.

SUMMARY

The following presents a summary of this disclosure to provide a basicunderstanding of some aspects. This summary is not intended to identifykey or critical elements or define any limitations of embodiments orclaims. Furthermore, this summary may provide a simplified overview ofsome aspects that may be described in greater detail in other portionsof this disclosure.

A drivetrain may include a ring gear and a weld ring. The ring gear andthe weld ring may comprise a weldable material. The weld ring may beovermolded with a ferrous material that may be not suitable for welding.The ferrous material may be a differential case or a shaft. The weldring may comprise a material that is weldable with the ring gear. Thismay allow the ring and the ring gear to be welded together.

A differential assembly may include a case, a weld ring, and a ringgear. The case may overmold the weld ring. The weld ring may be weldedwith the ring gear. The ring gear may comprise a first material and thecase may comprise a second material.

A shaft for a drivetrain may include a shaft body, a ring gear, and aweld ring. The weld ring may be overmolded with the shaft body. The weldring and shaft may be machined to specifications. The ring gear may bewelded to the weld ring.

A method of manufacturing a drivetrain component may allow for couplinga ferrous component with a weld ring and welding the weld ring to a ringgear. The method may include forming the ferrous component of a firstmaterial. The ferrous component may be joined with a weld ring formedfrom a second material. The weld ring may be welded to a ring gearformed of a third material.

The following description and the drawings disclose various illustrativeaspects. Some improvements and novel aspects may be expresslyidentified, while others may be apparent from the description anddrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings illustrate various systems, apparatuses,devices and related methods, in which like reference characters refer tolike parts throughout, and in which:

FIG. 1 is a side, cross-sectional view of a differential assemblycomprising a case, a weld ring and a ring gear in accordance withembodiments disclosed herein;

FIG. 2 illustrates a side, perspective view of the differential assemblyof FIG. 1 in accordance with embodiments disclosed herein;

FIG. 3 illustrates another side, perspective view of the differentialassembly of FIG. 1 in accordance with embodiments disclosed herein;

FIG. 4 is a cross sectional view of a differential assembly comprising acase with a fastener coupled to a weld ring in accordance withembodiments disclosed herein;

FIG. 5 illustrates an exemplary weld ring comprising protrusions formedon an inner surface in accordance with embodiments disclosed herein;

FIG. 6 illustrates an exemplary weld ring comprising cut outs formed onan inner surface in accordance with embodiments disclosed herein;

FIG. 7 illustrates an exemplary weld ring comprising circular cut outsformed on an inner surface in accordance with embodiments disclosedherein;

FIG. 8 illustrates an exemplary weld ring comprising depressions formedon an inner surface in accordance with embodiments disclosed herein;

FIG. 9 illustrates a perspective view of another exemplary weld ringcomprising protrusions formed on an inner surface in accordance withembodiments disclosed herein;

FIG. 10 illustrates an exploded view of a differential case overmoldedwith a weld ring, and a ring gear in accordance with embodimentsdisclosed herein;

FIG. 11 illustrates a cross sectional view of a differential case withan axial weld in accordance with embodiments disclosed herein;

FIG. 12 illustrates a cross sectional view of another differential casewith an axial weld in accordance with embodiments disclosed herein;

FIG. 13 illustrates a cross sectional view of a differential case with aradial weld in accordance with embodiments disclosed herein;

FIG. 14 illustrates a perspective view of a shaft assembly with a weldring and a ring gear in accordance with embodiments disclosed herein;

FIG. 15 illustrates a partial cross sectional view of a ring gear, weldring, and shaft body of the shaft assembly of FIG. 14 in accordance withembodiments disclosed herein;

FIG. 16 illustrates a cross sectional view of the shaft assembly of FIG.14 after or during a casting process in accordance with embodimentsdisclosed herein;

FIG. 17 illustrates a cross sectional view of the shaft assembly of FIG.14 after or during a machining process in accordance with embodimentsdisclosed herein;

FIG. 18 illustrates an exemplary method of manufacturing a component fora drivetrain of a vehicle in accordance with embodiments disclosedherein; and

FIG. 19 illustrates an exemplary method of manufacturing a component ofa drivetrain of a vehicle including machining the component and a weldring in accordance with embodiments disclosed herein.

DETAILED DESCRIPTION

Reference will now be made to exemplary embodiments, examples of whichare illustrated in the accompanying drawings. It is to be understoodthat other embodiments may be utilized, and structural and functionalchanges may be made. Moreover, features of the various embodiments maybe combined or altered. As such, the following description is presentedby way of illustration only and should not limit in any way the variousalternatives and modifications that may be made to the illustratedembodiments. In this disclosure, numerous specific details provide athorough understanding of the subject disclosure. It should beunderstood that aspects of this disclosure may be practiced with otherembodiments not necessarily including all aspects described herein, etc.

As used herein, the words “example” and “exemplary” mean an instance, orillustration. The words “example” or “exemplary” do not indicate a keyor preferred aspect or embodiment. The word “or” is intended to beinclusive rather than exclusive, unless context suggests otherwise. Asan example, the phrase “A employs B or C,” includes any inclusivepermutation (e.g., A employs B; A employs C; or A employs both B and C).As another matter, the articles “a” and “an” are generally intended tomean “one or more” unless context suggest otherwise.

Embodiments described herein may refer to welding or laser welding.Laser welding may include utilizing a laser or laser beam to joinmultiple pieces of metal. The laser beam delivers concentrated heat,which may be particularly suitable for high welding rates and localizedheat applications. It is noted that embodiments may utilize otherwelding techniques such as electron beam welding, arc welding,laser-hybrid welding (e.g., combination of laser beam welding and arcwelding), or the like.

While embodiments and examples describe a differential or shaft for avehicle, it is noted that the systems, apparatuses, and methodsdescribed herein may be applied to a variety of applications, includingautomobiles, aircrafts, personal transport systems (e.g., motorizedscooters), or the like. As such, references to a vehicle are used asexemplary embodiments for purposes of explanation and clarity. It isnoted that the present teachings may not be limited to such examples.

A vehicle, as used herein, may comprise an axle assembly, engine (e.g.,gas, electric, etc.), frame, transmission, drive shaft, anddriven/non-driven wheels. The engine generally produces an output orpower (e.g., torque). A transmission may alter speed and torque of theoutput produced by the engine. The transmission may transmit the torqueto a drivetrain. The drivetrain may include a drive shaft that drivesthe axle assembly. In an aspect, the drivetrain may include adifferential as described herein. The axle assembly drives wheels of thevehicle.

A differential generally includes a housing or case, and a number ofgears, pinions, and the like. The gears and pinions may be referred toas a gear set. This gear set may allow for operation of wheels of avehicle at different speeds. For example, when a vehicle turns, a firstor inner wheel (e.g., the wheel at the inner curve of the turn) may bedriven at a lower speed than a second or outer wheel. This may result inincreased control of the vehicle in comparison to vehicles that do notinclude a differential.

In some systems, such as automotive systems, the components of adrivetrain (e.g., propeller shaft, lay shaft, a differential, etc.) maybe subject to forces that require the components to have a certainstrength. For instance, automobiles (e.g., cars, trucks, farm equipment,etc.) may require components to be formed of ferrous materials (e.g.,iron, cast iron, steel, etc.). It is noted that drivetrains for vehiclesmay experience a number of forces and may be subject to constraints(e.g., cost, shape, weight, strength, etc.). Further, as drivetrainscontain moving, or non-static, components, there may be uniquechallenges that are not present in other fields. Many of these uniquechallenges and issues are addressed by various disclosed aspects.

In applications, some components of the differential may not need tohave the strength of steel. Different materials can be used forapplications where steel is not needed or where weldability is notneeded for the bulk of the component. This may allow for reduced weightof the differential, more efficient assembly, or the like. One suchapplication may allow a differential housing to be made of nodular orductile iron or a non-ferrous material (e.g., aluminum, etc.). Adifferential housing or other component, such as a lay shaft, may beovermolded onto a different material, such as a low-alloy, mild, orplain-carbon steel ring that is suitable for welding. Examples ofweld-friendly or suitable-for-welding materials include low-carbonlow-alloy steels, steels having a carbon equivalent of less than 0.40%according to the International Institute of Welding equation, etc. Whileembodiments may refer to steel, it is noted that other materials may beutilized, such as aluminum, magnesium, copper, lead, nickel, tin,titanium, zinc, alloys, or the like. Such materials may not have thesame strength as ferrous materials, but may be lighter weight, cheaper,and/or more than sufficient for certain applications.

A cast-in ring or insert may allow for welding of a gear to a shaft or adifferential assembly. For instance, a ferrous material ring, suitablefor welding, may be cast into a casting material that is not suitablefor welding. A ring gear may then be welded to the cast-in ring. Thus,the ring gear is welded to a weld-friendly material. This may allow forreduced (e.g., eliminated) cracking associated with welding highpearlitic nodular material to steel parts. In another aspect, this mayreduce (e.g., eliminate) the need to use preheating systems or methodsto weld nodular material with steel parts or other parts.

For instance, laser welding a nodular or ductile iron part to a steelpart may result in cracking in the nodular part. The heat affected zoneof the nodular iron part from laser welding may contain brittlemicrostructural constituents. This may lead to cracking from residualstress, high cooling rates, or the like. In some instances, parts may bepreheated for welding. The techniques for preheating may be expensiveand time consuming. The present disclosure may solve these as well asother issues.

As an example, as consumers become more conscious of fuel savingautomobiles, vehicle weight becomes more important. Moreover, lighterweight vehicles may place a reduced amount of stress on a drivetrain incomparison with heavier, traditional vehicles. For these and otherreasons, components of a drivetrain may be made of lighter weightmaterials than conventional systems, disclosed apparatuses and methodsmay reduce production steps, costs, and/or reduce the number ofcomponents of the differential.

In at least one embodiment, a differential case may comprise a castablemetal that is cast within and/or about a portion of a weld ring. Inother embodiments, the weld ring may comprise a castable metal that iswithin or about a portion of the differential case. The case and theweld ring may comprise different materials. For instance, the case maycomprise iron (e.g., a nodular iron) and the weld ring may comprisesteel (e.g., low-alloy steel, mild steel, etc.). A ring gear may bewelded to the weld ring, such as via laser welding. It is noted that thering gear may be welded such that the weld joint is only between theweld ring and the ring gear.

The ring gear may comprise steel or another metal having a desiredstrength for driving pinions and/or wheel axles. The ring gear may beformed as a substantially circular ring. It is noted that the ring gearmay or may not have teeth formed thereon during the casting or weldingprocess. For instance, if the teeth are formed prior to welding, theymay be damaged or deformed during the welding process. Thus, the teethmay be formed after welding. When formed after welding, the teeth may besubsequently hardened, such as through an induction hardening process.It is noted that the teeth may be formed prior to welding and may beprotected by a protective member or otherwise protected.

Turning now to the figures, FIGS. 1-3 illustrate an exemplarydifferential assembly 100. The differential assembly 100 may primarilycomprise a case 110, weld ring 130, and a ring gear 150. It is notedthat the differentially assembly 100 may include other components suchas pinions (not shown), gears (not shown), machined apertures, or thelike. In another aspect, while depicted as comprising a beveled ringgear 150, the ring gear may comprise a helical ring gear (see, e.g.,FIG. 10).

Case 110 may comprise a body 116 and a flange 112. The body 116 mayoperatively house one or more gears, pinions, or the like. The flange112 may extend from the body 116. In an aspect, the flange 112 may begenerally circular, cylindrical, or the like. Body 116 and flange 112may be monolithically formed and/or may be separately formed and joinedtogether. According to at least one embodiment, body 116 and flange 112may be formed of or comprise a first material, such as nodular material.In an aspect, the nodular material may be a ferrous material, such asiron and/or iron alloys. It is noted that the first material maycomprise a different material than the material that makes up weld ring130 and/or ring gear 150, as described in more detail herein. Forinstance, the case 110 may comprise a nodular iron that may be cast intoa desired shape and the weld ring 130 and ring gear 150 may comprisesteel. It is noted that certain geometric aspects may be machined intothe case 110, weld ring 130, and/or ring gear 150 after casting,welding, or the like.

Weld ring 130 may comprise a generally ring-shaped body 132. The body132 may be cast in or about the case 110. In an example, the body 132may be formed and the case 110 may be overmolded within the body 132. Itis noted that the order of casting or overmolding may depend on thetypes of materials utilized, a manufacturing process, or other designfactors. For sake of brevity, embodiments generally refer to the body132 being cast about the case 110. In an aspect, a protrusion 134 mayextend from the body 132 and into a via or groove 114 of the flange 112of case 110. The groove 114 and protrusion 134 may provide a joint thatcompensates for forces (e.g., torque, etc.) that may affect the weldring 130. For example, the differential assembly 100 may be subject tovarious forces during operation of a vehicle. The groove 114 andprotrusion 134 may provide a locking mechanism or anchor that generallyprevents or reduces the possibility of slippage between the case 110 andthe weld ring 130. While differential assembly 100 is illustrated withthe groove 114 and protrusion 134, it is noted that other geometricformations or features may be utilized for the joint.

Turning to FIGS. 5-9, there are weld ring 500, weld ring 600, weld ring700, weld ring 800, and weld ring 900. It is noted that like-namedcomponents of weld rings 500-900 may comprise similar aspects, unlesscontext suggests otherwise or warrants a particular distinction amongthe terms. For instance, the weld rings 500-900, may comprise similar orthe same materials.

As shown, the weld rings 500-900 may comprise out-of-plane or3-dimensional features. Such features comprise geometric patterns orformations that allow cast-in material to flow in, around, through, orotherwise about the formations. For instance, the features prevent thejoint of a protrusion and groove from being coplanar.

FIG. 5 illustrates weld ring 500 comprising a plurality of protrusionsor nodes 524 extending from an inner ring 536 disposed proximal innersurface 518. The nodes 524 may be separated by cutouts 532. When a caseor shaft is casted, it may fill the cutouts 532 and interlock with nodes524.

FIG. 6 illustrates weld ring 600 comprising a plurality of cutouts 624disposed within an inner ring 636. The inner ring may extend from innersurface 618 of the weld ring 600. When a case is casted, it may fill thecutouts 624 to interlock with the weld ring 600. The cutouts 624 maycomprise any desired shape, such as polygonal, rectangular, elliptical,irregular in shape, or the like. For instance, FIG. 7 illustrates a weldring 700 comprising a plurality of generally circular cutouts 724. Invarious embodiments, cutouts 624, 724 may extend entirely through thering (e.g., holes, passages, orifices, etc.) or only partially throughthe ring (e.g., divots, depressions, etc.).

FIG. 8 illustrates weld ring 800 that may comprise depressions 824 and832 formed in an inner ring 836. In an aspect, the depressions 824 and832 may alternate sides of the inner ring 836. The depressions 824 and832 may comprise any desired shape, such as polygonal, rectangular,elliptical, irregular in shape, or the like. When material is castaround the depressions 824 and 832 the material may fill the depressions824 and 832. This may allow a case to be cast into the weld ring 800 andlockable secure thereto.

FIG. 9 illustrates weld ring 900 that may comprise notches orprotrusions 924 formed in an inner ring 936. The notches 924 maycomprise any desired shape, such as polygonal, rectangular, elliptical,irregular in shape, or the like. When material is cast around theprotrusions 924 the material may fill or surround the protrusions 924.This may allow a case to be cast into the weld ring 800 and lockablesecure thereto.

The formations described here as well as elsewhere may allow fortransmission of torque from a ring gear to another operable component(e.g., a shaft, a differential case, etc.). For instance, a differentialcase or a shaft may be overmolded with the weld ring. The features ofthe weld ring may allow the material of the case or a shaft to flow intoor about the feature. This may prevent slippage during rotation of acase or shaft. In another aspect, the out-of-plane features facilitatebonding and resist separation of the materials during shrinkage as thecast material cools. The features of the weld ring may prevent or reducedisengaging between the material and the weld ring. Turning back to FIG.1, the weld ring 130 may comprise a second material, which may be adifferent material than the material of the case 110. For instance theweld ring 130 may comprise a steel material, such as mild steel (e.g.,plain-carbon steel), or the like. It is noted that weld ring 130 maycomprise other materials that may be selected for a desired application.The second material may be selected such that it may be operativelywelded to the ring gear 150.

According to at least one embodiment, the ring gear 150 may comprise abody 152 that comprises a third material, which may be different fromthe material of the case 110 (e.g., the first material). In anotheraspect, the third material may be the same or different material as thatof the weld ring 130 (e.g., the second material). For instance, the ringgear 150 may comprise steel, such as forged steel or other steel thatmay be appropriate for the forces to which the ring gear 150 is exposedduring operation of a vehicle. Weld ring 130 may also comprise steel,which may be the same or different type of steel as that of ring gear150. For example, weld ring 130 may not be subject to the same forces asring gear 150, which may allow for use of a weaker steel (e.g., mildsteel). As described herein, case 110 may comprise iron, such as ahigher pearlitic content nodular iron or the like. As such, the weldring 130 may provide a surface for which the ring gear 150 may be weldedwithout the need for preheating and/or without many issues related tothermal mismatch between steel and iron materials.

In one or more embodiments, the ring gear 150 may include a flange 154or other connection portion that may be joined to a flange 136 of weldring 130. Joining may include welding the flange 136 and flange 154 at aweld joint 102. The weld joint 102 may comprise a weld 104 that joinsthe flange 136 of weld ring 130. It is noted that the weld joint 102 mayinclude an expansion area 106, which may comprise a cavity formedbetween the weld ring 130 and the ring-gear 150.

It is further noted that ring gear 150 may be formed or pre-manufacturedwithout teeth. This may prevent damage to sprockets or teeth duringwelding. Thus, after the case 110, weld ring 130, and ring gear 150 areassembled, the teeth (not shown) may be formed on a surface 156 of ringgear 150. For example, the teeth may comprise curved grooves formed insurface 156. These teeth may interact with pinions or gears that maydrive an axle of a vehicle. According to at least one embodiment, theteeth may be pre-formed in the ring gear 150 prior to attaching the ringgear 150 to the weld ring 130.

In an aspect, the teeth may comprise an input member that mayoperatively receive torque from an engine, such as via a pinion gear,drive shaft or the like. The ring gear 150 may transfer the torque viathe weld joint 102. The weld joint 102 may transmit the torque to theweld ring 130 and the case 110. Case 110 may rotate and may transmit thetorque to one or more gears (e.g., side gears, spider gears, etc.). Itis noted that the weld joint 102, weld ring, case, and/or gears may beconsidered an output member for the ring gear 150.

The teeth may be hardened after they are formed or machined. In anaspect, the ring gear 150 and the weld ring 130 may be subjected tocoefficient of thermal expansion mismatch. Because of this mismatch,some hardening techniques would weaken and/or damage weld joint 102. Assuch, localized hardening techniques may be utilized to harden theteeth. For instance, induction hardening may target the teeth withlocalized heat treatment. This will localize the heat or hardeningprocess such that the weld ring 130 and/or weld joint 102 maintains itsintegrity and desired properties.

It is noted that various materials may be utilized for the case 110,weld ring 130, and/or ring gear 150. These components may comprisedifferent materials, such that weld ring 130 and ring gear 150 may bewelded together, and wherein the ring gear 150 and case 110 aregenerally not weldable together without first heat treating thecomponents or applying other techniques.

In another aspect, weld ring 130 and case 110 may be joined togetherutilizing various techniques other than overmolding. For instance, theweld ring 130 may be fastened to the case 110 via one or more fasteners(e.g., screws, bolts, rivets, etc.). It is further noted that variousdisclosed aspects may be combined. In an example, the weld ring 130 maybe cast-in the case 110 and fastened to the case 110 via a fastener.

Turning to FIG. 4, there is a differential assembly 200 comprising aring gear 250, and a case 210 that is coupled to a weld ring 230 via atleast one fastener 206. It is noted that differential assembly 200 maycomprise the same, similar, or different aspects as those described withreference to differential assembly 100. For instance, the materialsutilized for case 210, weld ring 230, and ring gear 250 may be the samematerials utilized for case 110, weld ring 130, and ring gear 150,respectively.

As illustrated, the weld ring 230 may comprise a body 232 and a flange234. The flange 234 may be received by a groove 214 formed in a flange212 of the case 210. In an aspect, the weld ring 230 may be cast-in thecase 210. An aperture may be formed through the flange 234 and theflange 212 such that a fastener 206 may be inserted therethrough. It isnoted that the fastener may comprise a bolt, screw, or the like. Afterinsertion, the faster 206 may be secured to the case 210 and/or weldring 230 via a nut or other threaded member.

In an aspect, the fastener 206 may comprise an anchor point or the likethat may prevent slippage or between the weld ring 230 and the case 210.For example, the ring gear 250 may be subject to various forces. Torquemay cause the ring gear 250 to pull the weld ring 230. Fastener 206 mayprovide an anchor or the like that may prevent or reduce the ability forweld ring 230 to separate from the case 210. Moreover, it is noted thatthe differential assembly 200 may comprise any number of fasteners. Inat least one aspect, the out-of-plane formations described herein maycomprise fasteners and may prevent or reduce separation between weldring 230 and case 210.

Turning to FIG. 10, there is a differential assembly 1000. Thedifferential assembly 100 may primarily include a case 1010, a weld ring1030, and a ring gear 1050.While shown as a helical-type gear, it isnoted that ring gear 1050 may comprise various other types of gears asdescribed herein. Moreover, differential assembly 1000 may comprisesimilar aspects described with reference to the other disclosed figures.For instance, the case 1010 may comprise a ferrous material not suitablefor welding (e.g., ductile iron, gray cast iron, compacted graphiteiron, etc.), while weld ring 1030 and ring gear 1050 may comprise steelor other materials that are suitable for welding.

In an embodiment, weld ring 1030 may be formed and case 1010 may be castin to the weld ring 1030. It is noted that weld ring 1030 may bemachined after casting of the case 1010. For instance, weld ring 1030may comprise a ring of steel. Prior to casting, the weld ring 1030 mayor may not comprise features 1032 formed on outer surface 1034. Thefeatures 1032 may comprise ridges, threads, tabs, or the like. In anaspect, the features 1032 may be machined before or after overmolding ofthe case 1010. When machined after an overmolding process, the features1032 do not risk being damaged during the process.

Ring gear 1050 may include geometric features 1052 (e.g., projections,lips, tabs, etc.) disposed on an inner surface 1056 of the ring gear1050. The ring gear 1050 may be press-fit, friction-fit, or otherwiseplaced about the weld ring 1030. One or more of the geometric features1052 may interface with features 1032 of the weld ring 1030. In anaspect, the geometric features 1052 of the ring gear 1050 may includeone or more lips. The lips may comprise different parameters. Forexample, lips may extend from inner surface 1056 for different lengths.The lengths may allow for operative alignment of the weld ring 1030 asdescribed here as well as elsewhere in this disclosure.

It is noted that the inner surface 1056 of the ring gear and the outersurface 1034 of the weld ring may comprise additional or differentgeometric features that may generally provide mechanisms for securing oraligning inner surface 1056 and outer surface 1034. For instance, innersurface 1056 and outer surface 1034 may include splines, flutes,threads, tapered surfaces, channels, or the like. As described herein,the ring gear 1050 and weld ring 1030 may be welded together to securethe weld ring 1030 to the ring gear 1050.

FIGS. 11-13 are partial cross-sectional views of differential assembly1100, differential assembly 1150, and differential assembly 1180 andprovide examples of axial and radial welding between the weld ring andring gear. It is noted that each of the differential assemblies 1100,1150, and 1180 may include a first side gear 1170, a second side gear1172, one or more pinion or spider gears 1174 and a case 1176. It isnoted that the above listed components may operatively receive input(e.g., power or torque) from a drive shaft (not shown) that interactswith a ring gear. The ring gear may rotate the case 1176, which mayoperatively deliver power to the one or more spider gears 1174 viacross-pin 1178. The spider gears 1174 may operatively deliver power tothe first side gear 1170 and the second side gear 1172. The first sidegear 1170 may be coupled to a first wheel via a first axle shaft. Thesecond side gear 1172 may be coupled to a second axle shaft, which mayin turn be coupled to a second wheel.

Embodiments may utilize various construction or welding techniques. Forinstance, differential assembly 1100 and differential assembly 1150illustrate axial weld assemblies. Differential assembly 1180 illustratesa radial weld embodiment. It is noted that other welding techniques maybe utilized.

As described in herein, embodiments may include weld rings and ringgears having various parameters. The differential assembly 1100 mayinclude weld ring 1110 and ring gear 1120. The weld ring 1110 maycomprise inner surface formations 1112 that may allow case 1176 to formaround the formations 1112. In another aspect, weld ring 1110 mayinclude outer surface formations 1114 that may include one or moreprotrusions, ridges, or the like. It is noted that corners of the outersurface formations 1114 may be squared, tapered, chamfered, filleted, orthe like. The outer surface formations 1114 may interface withformations 1124 of the ring gear 1120. It is noted the formations 1124may comprise one or more protrusions, ridges, or the like, havingcorners that may be squared, tapered, chamfered, filleted, or the like.In an aspect, the outer surface formations 1114 may be welded to theformations 1124 such that ring gear 1120 and weld ring 1110 aregenerally secured together. As described herein, the welding may form aweld joint 1102. It is noted that the joint may include one or moreexpansion areas 1106.

FIG. 12 illustrates the differential assembly 1150 comprising weld ring1152 and ring gear 1160, which may comprise similar aspects as weld ring1110 and ring gear 1120 of differential assembly 1100. The weld ring1152 may comprise a first flange 1154 and a second flange 1156. Thefirst flange 1154 may generally extend a first distance away from thecase 1176 and the second flange 1156 may extend a second distance fromthe case 1176. The first distance may be generally lesser than thesecond distance.

Ring gear 1160, likewise, may comprise a first flange 1162 and a secondflange 1164. The first flange 1162 may generally extend closer to thecase 1176 than the second flange 1164. As such, the ring gear 1160 mayengage with the weld ring 1152 such that the first flange 1162 of thering gear 1160 abuts the first flange 1154 of the weld ring 1152. Thismay increase surface contact, prevent or reduce slippage, or otherwiseallow for more efficient construction of the differential assembly 1150.

FIG. 13 illustrates the differential assembly 1180 comprising weld ring1182 and ring gear 1190. In aspect, the contact area for weld ring 1182and ring gear 1190 may be generally larger than the contact areas ofdifferential assembly 1100 and differential assembly 1150. Weld ring1182 may comprise an L-like shape. A body 1184 may extend generallyparallel to the case 1176. The body 1184 may turn or bend upwards toflange 1186. The body 1184 and the flange 1186 may respectively contactinner surface 1192 and protrusion 1194 of the ring gear 1190.

FIGS. 14 and 15 are a shaft assembly 1400 for a drivetrain in accordancewith various disclosed aspects. The shaft assembly 1400 may generallyinclude a lay shaft or shaft 1410, a weld ring 1430, and a ring gear1450. It is noted that the shaft assembly 1400 may be a component of adrivetrain, such as a component in a power transfer unit, transfer case,transmission, or the like. It is noted that the shaft assembly 1400 maybe operatively deployed in other portions of a drivetrain, rear wheeldrive automobiles, all wheel drive automobiles, or the like. Embodimentsmay refer to front wheel drive automobiles for purposes of illustrationand brevity.

In at least one example, the shaft 1410 may be a shaft for a front wheeldrive vehicle with a disconnecting power transfer unit. For instance, anactuator may operatively position (e.g., slide or otherwise move) theshaft 1410 such that ring gear 1450 operatively changes a connectionstate (e.g., connects or disconnects) relative to a pinion gear or othergear. In such a manner, the ring gear 1450 may disconnect from a pinionto prevent or end power transfer to rear wheels. Similarly, the ringgear 1450 may connect to a pinion to send or enable power transfer torear wheels.

It is noted that the ring gear 1450 may generally comprise a materialthat is not weldable with a material of the shaft 1410. For instance,the ring gear 1450 may comprise a steel material and the shaft 1430 maycomprise ductile iron. It is noted that the ring gear 1450 and the shaft1410 may comprise other materials in accordance with various disclosedaspects.

According to an embodiment, shaft 1410 may include a mount member 1412.The mount member 1412 may comprise a seat or flange for receiving thering gear 1450. For instance, a flange 1414 of the mount member 1412 mayprotrude outwards from the shaft 1410. The flange 1414 may include aweld ring 1430 that may be overmolded by the flange 1414. The weld ring1430 may comprise a material that may be operatively welded with thering gear 1450. It is noted that the weld ring 1430 may comprise variousmaterials (e.g., steel, etc.) as described herein.

Turning to FIGS. 16-17, with reference to FIGS. 14-15, therecross-sectional views of the shaft 1410 at various stages ofmanufacturing. Stage 1600 illustrates a cast material 1602 (e.g., castductile iron) that overmolded a weldable material 1604. The castmaterial 1602 and weldable material 1604 may be machined down to moreprecise measurements and dimensions as shown in stage 1700. At stage1600, however, the cast material 1602 and weldable material 1604 maycomprise rough dimensions and unformed surface features. In an aspect,the features may be machined after casting. This may prevent damageduring the casting process.

At stage 1700, as shown in the shaded areas, weldable material 1604 maycomprise a waste area 1708 and a weld ring area 1706. The waste area1708 may generally represent material that is removed during a machiningprocess. The weld ring area 1706 may generally represent material thatwill be kept to form the weld ring 1430 of shaft 1410.

While embodiments may refer to weld ring as a ring, it is noted that inother embodiments a weld ring may not be a ring. For instance, a weldring may comprise disparate pieces or portions of material. In anexample, a weld ring may comprise two more portions of material that arenot physically connected to each other. In another aspect, a weld ringmay not be circular or elliptical in shape. Likewise, a weld ring maycomprise one or more rings.

In view of the subject matter described herein, methods that may berelated to various embodiments may be better appreciated with referenceto the flowchart of FIGS. 18 and 19. While the methods are shown anddescribed as a series of blocks, it is noted that associated methods orprocesses are not limited by the order of the blocks unless contextsuggests otherwise or warrants a particular order. It is further notedthat some blocks and corresponding actions may occur in different ordersor concurrently with other blocks. Moreover, different blocks or actionsmay be utilized to implement the methods described hereinafter. Variousactions may be completed by one or more of users, mechanical machines,automated assembly machines (e.g., including one or more processors orcomputing devices), or the like.

FIG. 18 is a flow chart of an exemplary method 1800 of manufacturing acomponent of a drivetrain as described herein. The method 1800 may beutilized to form a component of a drivetrain having a ring gear that isa different material than the component. For example, a differential maycomprise an iron case and a steel ring gear.

At 1802, a manufacturer may cast-in or overmold a weld ring (e.g., 130,230, etc.) with a component of a drivetrain (e.g., a differential case,a shaft, or the like). For instance, the weld ring may be positioned ina mold cavity or die, such as a die for a drivetrain component. It isnoted that positioning the weld ring may include other or additionalsteps, such as coating the die (e.g., with a lubricant, mold release,etc.), coating the weld ring, or the like.

At 1804, the manufacturer may weld the weld ring with a ring gear (e.g.,ring gear 150, 250, etc.). Welding may include laser welding or thelike. It is noted that this ring gear may comprise a steel material thatmay or may not be subject to a hardening process. In an aspect, the ringgear may be pre-manufactured then provided to another party that maycast materials. In an aspect, the ring gear may comprise steel, such asa forged steel.

FIG. 19 is a flow chart of an exemplary method 1900 of manufacturing acomponent of a drivetrain as described herein. As described herein, thecomponent may include a case of a differential, a shaft, or the like.

At 1902, a manufacturer may cast-in or overmold a weld ring (e.g., 130,230, etc.) with a component of a drivetrain (e.g., a differential case,a shaft, or the like). It is noted that the manufacturer may form theweld ring with extra material so that it may be machined in a laterstep. In another aspect, the component may be formed with extra materialso that it maybe machined in a later step. For instance, the weld ringmay be positioned in a mold cavity or die, such as a die for a componentof a drivetrain. It is noted that positioning the weld ring may includeother or additional steps, such as coating the mold cavity, coating theweld ring, or the like.

At 1904, the manufacturer may machine the weld ring and the component ofthe drivetrain. Machining may include cutting or otherwise forming theweld ring and drivetrain to desired specifications. For instance,component may be machined to include apertures for side gears, spidergears, or the like.

At 1906, the manufacturer may weld the weld ring with a ring gear (e.g.,ring gear 150, 250, etc.). Welding may include laser welding or thelike. It is noted that this ring gear may comprise a steel material thatmay or may not be subject to a hardening process. In an aspect, the ringgear may be pre-manufactured then provided to another party that maycast materials. In an aspect, the ring gear may comprise steel, such asa forged steel.

What has been described above includes examples of the presentspecification. It is, of course, not possible to describe everyconceivable combination of components or methodologies for purposes ofdescribing the present specification, but one of ordinary skill in theart may recognize that many further combinations and permutations of thepresent specification are possible. Each of the components describedabove may be combined or added together in any permutation to defineembodiments disclosed herein. Accordingly, the present specification isintended to embrace all such alterations, modifications and variationsthat fall within the spirit and scope of the appended claims.Furthermore, to the extent that the term “includes” is used in eitherthe detailed description or the claims, such term is intended to beinclusive in a manner similar to the term “comprising” as “comprising”is interpreted when employed as a transitional word in a claim

What is claimed is:
 1. A differential assembly comprising: a case comprising a first material; a weld ring joined to the case and comprising a second material that is different from the first material; and a ring gear coupled to the weld ring, wherein the ring gear operatively receives torque from an engine, and wherein case operatively transmits torque to one or more wheels.
 2. The differential assembly of claim 1, wherein the ring gear comprises a third material, wherein the third material is a different material than the first material.
 3. The differential assembly of claim 2, wherein the third material is different from the second material.
 4. The differential assembly of claim 2, wherein the third material comprises steel and the first material comprises ductile iron.
 5. The differential assembly of claim 1, wherein the second material comprises steel and the first material comprises ductile iron.
 6. The differential assembly of claim 1, further comprising a weld joint coupling the weld ring and the ring gear.
 7. The differential assembly of claim 6 wherein the weld joint comprises at least one expansion area.
 8. The differential assembly of claim 1, wherein the case is overmolded onto the weld ring.
 9. The differential assembly of claim 1, wherein the ring gear operatively couples to a drive shaft and operatively rotates relative the drive shaft.
 10. A shaft of a drivetrain for providing torque to a component of the drivetrain, the shaft comprising: a weld ring comprising a first material that is suitable for welding; a shaft body comprising a second material overmolded onto the weld ring, wherein the shaft body operatively provides torque to wheels; a ring gear welded to the weld ring, wherein the ring gear operatively receives torque from an engine.
 11. The shaft of claim 10, wherein the first material is steel and the second material is ductile iron, and wherein the of the shaft body is cast over the weld ring.
 12. The shaft of claim 10, wherein the shaft is a differential case.
 13. The shaft of claim 10, wherein the weld ring comprises an inner surface that includes at least one out-of-plane formation.
 14. The shaft of claim 13, wherein the at least one out-of-plane formation engagedly secures the weld ring with the shaft body.
 15. A method of manufacturing a component of a drivetrain for a vehicle comprising: forming teeth in the ring gear, wherein the teeth are configured to operatively receive torque from another component of the drivetrain; overmolding a weld ring formed of a first material that is suitable-for-welding with a second material that is not suitable-for-welding; welding a ring gear to the weld ring.
 16. The method of claim 15, wherein welding comprises laser welding the weld ring to the ring gear.
 17. The method of claim 15, wherein welding comprises at least one of axially or radially welding the ring gear to the weld ring.
 18. The method of claim 15, further comprising machining the weld ring and the second material after the overmolding and prior to the welding.
 19. The method of claim 15, further comprising machining the weld ring prior to the overmolding.
 20. The method of claim 20, further comprising hardening the teeth of the ring gear. 